Have the OEM BPVs changed over the years? Yes. 08+ Subarus have a BPV that is plastic. So if you for some reason you have a plastic BPV, it will not hold as much boost as the old metal ones. The plastic ones will only hold ~17PSI give or take.
I have a 2012 WRX stage 2 pumping out 19.5 PSI. Is my plastic BPV leaking?